Global Warming

We would like to thank Climate Positive and Dr Pearman for the following information

Without the atmosphere, the Earth would be around 33 degrees cooler than it is today, and current life on this planet could not be sustained. The atmosphere is comprised of transparent gases which allow heat from the sun to penetrate through, and then to radiate back out to space. Like a greenhouse, the atmosphere keeps the surface of the earth warmer than it would otherwise be. As the earth radiates heat, ‘greenhouse gases’ retain some of that heat in the atmosphere, enhancing the surface temperature of the Earth. The main greenhouse gases are carbon dioxide (CO2), methane (CH4), water vapour and nitrous oxide (N2O).

Humans have increased the concentrations of greenhouse gases in the atmosphere, and this has ‘enhanced’ the natural greenhouse effect. The surface temperature of the Earth is warming, because there are more greenhouse gases in the atmosphere absorbing more of the radiating heat. Scientists are now studying the effects of an ‘enhanced greenhouse effect’. Their findings so far indicate that major climatic changes including rising sea levels, melting glaciers, more severe droughts and floods, and severe storm activity are resulting from increasing surface temperatures.

The Climate System and the Carbon Cycle
The combustion of coal, oil and gas is the primary reason for atmospheric concentrations of carbon dioxide increasing; therefore, human activity is changing the Earth’s climate. We burn fossil fuels for heating, cooling, transport, business and industry.

But there is more going on in the carbon cycle than that. The oceans also have a role in determining the amount of carbon dioxide in the atmosphere. Depending on their temperature and chemical properties, the oceans have the ability to remove up to 2 giga-tonnes of carbon from the atmosphere each year. Considering humans have been adding carbon to the atmosphere at an average rate of 8Gt annually over the past 100 years or so, the concentrations of carbon are increasing at a rate of just under 1% per year. Already the carbon concentration has increased 32% in this period. Plants also interact with the carbon cycle. Through photosynthesis, plants extract carbon from the atmosphere at a rate of about 50Gt a year, yet most of this is replaced by respiration in the same period. Deforestation and other land-use change also releases carbon into the atmosphere.

Carbon dioxide concentrations in the atmosphere are not constant, as there are small imbalances in the way carbon is released and absorbed. While scientists can’t know the future, high-precision observatories and monitoring stations around the globe are used to identify what is happening. Scientific observations produce accurate measurements of past and current carbon concentrations, and provide an idea of what may come.

Modeling Climate Behaviour
Scientists around the world are working to understand how changes in atmospheric concentrations of greenhouse gases are influencing the global climate system. This is a highly complex task as there are many aspects of the climate system which must be measured and understood.

Dr Graeme Pearman explains here what scientists must come to terms with in order to be confident in their models.

Scientists must understand ‘how sunlight penetrates the Earth’s atmosphere, including being partially reflected by clouds or dust and heats the Earth’s surface; how this heating varies from day to day, season to season, and Equator to Pole, influencing the regional heating rates of the Earth and how the climate responds. But further, it involves understanding how this heat is then redistributed by the circulation of the atmosphere and the oceans as they respond to the uneven heating, and by the evaporation of water which transfers energy into the atmosphere and drives some of the circulation processes (eg. tropical storms); and how that water is condensed to form clouds that influence the reflection of sunlight or is precipitated elsewhere as part of the climate system.’ No easy task!

Scientific findings so far.....
The Intergovernmental Panel on Climate Change (IPCC) was established to periodically review the outcomes of research and the modelling of how the climate system is being affected by increased concentrations of greenhouse gases. The IPCC comprises thousands of scientists from many countries and disciplines. They have produced three assessment reports so far, with another due this year. The key IPCC findings from the third assessment report are:

• Over the past century the planet warmed by 0.4-0.8 degrees Celsius.

• Models indicate that most of the warming over the past 50 years was due to human activity.

• Further warming this century is likely, reaching 1.4-5.8 degrees Celsius, with a sea-level rise of 9-88 cm by 2100.

• Reducing greenhouse gas emissions will delay and reduce climate-change induced damage.

Climate Changes to Date
We all know the climate can be variable, not just season to season, year to year, but sometimes in one day. You may live somewhere where there seem to be four seasons in one day, and the temperature can drop dramatically within minutes. It is therefore impossible to identify long-term changes in the climate using local or regional data alone.

Scientists use global climate data dating back 150 years, to when records first began. From this, it’s evident the surface temperature of the Earth has increased 0.7 degrees Celcius over the past 100 years. The temperature of the deep oceans has also increased, but not by as much. We are already experiencing changes because of this warming.

Sea levels have risen 18 cm around the world over the past 100 years – primarily because the water expands as it warms, but also because of ice melt.

De-glaciation is affecting major ice and snow regions of the world. Scientific observations show that Arctic sea-ice is 40% thinner, and reduced in area by 8% from what it was 25 years ago. Glaciers around the world are receding, and the snow season is about one month shorter in parts of the northern hemisphere.

Other impacts have been observed, including changes to biological systems, increased storm intensity and altered rain patterns, which are making some regions wetter and others more prone to drought. The much publicised Hurricane Katrina, which devastated New Orleans in the United States, and Cyclone Larry, which flattened a number of towns and agricultural areas in North-Eastern Australia, are examples of the kinds of intense storms being experienced. Storm frequency has not changed, but storms classified categories 4 and 5 have increased by 100%. The theory is that warmer ocean and surface temperatures provide more energy for intense storm development.

Projections for the Future
All of the Intergovernmental Panel on Climate Change’s projections for the future anticipate continued increases in greenhouse-gas concentrations, and therefore further warming of the Earth’s surface temperature. The IPCC has devised models for various alternative futures, to take into account human decisions about energy use and reduction.

The IPCC anticipates the global temperature will rise between 1.4 and 5.8 degrees Celsius this century. Even if there is no further increase in greenhouse-gas concentrations, the Earth is still committed to a 0.5-1.0 degree Celsius warming, due to past activity. Of course, this will affect us all differently depending on which region of the world we live in. Future changes will require communities to adapt to changing climatic patterns, and mitigate against further warming.

Why Global Action is Taking so Long
Although the burning of fossil fuels has already committed the Earth to warming at least 0.5-1.0 degree, mitigating further warming is essential to reduce adverse impacts on the global climate system. The United Nations Framework Convention on Climate Change (FCCC) was established to ‘prevent dangerous anthropogenic interference with the climate system’.

Global leaders have had to work out what an ‘acceptable’ rise in surface temperature is, in order to set limitations on the amount of carbon dioxide being released into the atmosphere. These limitations need to be binding across the world in order for greenhouse-gas concentrations to stabilise. Gaining a consensus on an ‘acceptable’ temperature rise and on what is ‘dangerous’ change is no simple task, as some communities will be advantaged by increasing temperatures, while others will be severely disadvantaged.

The Kyoto Protocol came into effect in 2005 and sets binding greenhouse-gas emission targets for signatories from the developed world. However, the United States and Australia have refused to ratify this protocol, and developing countries, particularly China and India, which have increasing emissions, do not have binding targets.

The European Union has chosen a warming of 2 degrees Celsius as its strategic guide for ‘acceptable’ change. To limit warming to this level will require massive reductions in current emission levels. And even so, scientists believe a rise of 2 degrees will bring about significant change to the physical and biological appearance of the Earth.

Energy Futures and Mitigation
If it’s energy generation and use which is the root of the greenhouse problem, it is here where we can look for ways to mitigate greenhouse-gas production. Australia has one of the highest per-capita greenhouse footprints in the world (28 tonnes of CO2 per person, 18.1 tonnes per household) because of its dependence on fossil fuels (Click here to work out your individual greenhouse footprint using Climate Positive’s calculator). This is because in Australia around 90% of energy production comes from fossil fuels, more than 55% of which comes from stationary electricity generation. With this kind of dependency, many changes can be made to reduce greenhouse gas emissions.

Energy Efficiency
Most households, offices and factories use energy inefficiently. Not only is this a waste of valuable resources, it comes at an unnecessary cost to the consumer and the environment. Small changes to energy-use habits can dramatically reduce energy consumption and energy bills. For examples of how this can be done, check out Climate Positive’s greenhouse calculator and list of reduction methods. You can also refer to Climate Positive’s energy saving tips, for the top 10 ways you can save energy around your house.

Technology Improvements
Many countries, including Australia, depend heavily on old and outdated coal fired power stations. Improving the efficiency of these power stations using existing available technologies could reduce Greenhouse gas output by 10%.

Changes to Fuel Mix
Electricity consumers in Australia have the opportunity to choose ‘Green electricity’ products from their electricity supplier. This is a way for individual customers to support less polluting forms of electricity production, like renewable energy and gas. If changes to the fuel mix were made across the board this could bring about reduced emissions. For instance, brown coal emits around double the carbon dioxide as black coal, and black coal twice that of gas.

Decentralised Electricity Generation
Centralised power stations provide most of the energy to large cities like Melbourne; however, half of the energy generated is lost as waste heat and in its transmission over long distances. If some buildings were self-sufficient in energy, the system would become much more efficient. This is called co-generation plants, where waste heat can be utilised rather than wasted, which can bring about greenhouse and cost savings.

Improved Vehicle Efficiency
Driving a car around our cities not only produces greenhouse gases, but reduces air quality. Hybrid cars use about half the fuel and emit just 10% of the air pollutants as vehicles using the conventional combustion engine. Hybrid vehicles are not yet commonplace, but as more are released to the market, we will see reductions in CO2 emissions and improvements in human health and air quality.

Renewable Energy
The most iconic renewable energy sources are wind turbines and solar (photovoltaic) panels. These can be used to generate power for homes, and also for whole communities if power stations are large enough. There are also other renewable energy sources, including small and large-scale hydroelectric plants, tidal and wave technologies, geothermal and biomass generation. The Australian Government supports renewable energy installation through its Mandated Renewable Energy Target of increasing Australia’s renewable generation by 9500 Giga-watt hours by 2010. Unfortunately, this target has not been increased or expanded.

Carbon Dioxide Geo-Sequestration
There are a number of proposals to reduce the carbon dioxide emissions of large power plants by storing the CO2 they produce underground. Known as geo-sequestration, this technology is being investigated for use in Australia. At this stage this technology is unproven, and likely to be expensive to implement.

Nuclear
The debate about the use of nuclear technology has intensified over recent years. A number of countries, particularly in Europe and Asia, are looking to nuclear power as a way of reducing their greenhouse gas emissions.

Consumer Action What You Can Do
Every one of us contributes in some measure to our national greenhouse footprint, and therefore we are all contributing to the measurable changes to the climate system. There’s opportunity for each of us to reduce our footprint, and even become Climate Positive by making some changes to lifestyle and energy use patterns.

One method of doing this is to assess your greenhouse footprint, which means working out how many tonnes of greenhouse gas is associated with your lifestyle. You can then reduce your footprint by making simple changes to your home energy use and supply, choice of transport, your diet and your personal investments.

Once you have reduced your personal footprint, you can then become Climate Positive by investing in replanting locally indigenous trees on deforested country, which will absorb an amount of carbon dioxide greater than you produce. Tree planting is the third important step you can take to reduce your personal impact on the planet.